Talk:Using multiple models in an MVC component
From Joomla! Documentation
It is worth to remember about prefix:
$model =& $this->getModel( 'Customer','CustomersModel' );
in this example the framework will attempt to find class CustomersModelCustomer
Lack of the model prefix may cause the following: Fatal error: Call to a member function getName() on a non-object in {...}/libraries/joomla/application/component/view.php on line 449